We lay out a theoretical framework to evaluate watermarking techniques for intellectual property protection (IPP). Based on this framework, we analyze two watermarking techniques for the graph coloring(GC) problem . Since credibility and overhead are the most important criteria for any efficient watermarking technique, we derive formulae that illustrate the trade-off between credibility and overhead. Asymptotically we prove that arbitrarily high credibility can be achieved with at most 1-color-overhead for both proposed watermarking techniques.